A smart, compelling novel unfolds in the wake of an event very much like the Rapture and revolves around those left behind.

The two most moving scenes in Tom Perrotta's sixth novel, "The Leftovers," come late in the book. In the first, Kevin Garvey — abandoned husband, distracted father, mayor of the affluent suburb of Mapleton — tells a woman he's been dating that he's just heard from his college-age son for the first time in months. "Were you close?" she asks, herself a bit distracted. "He was my little boy, I was always so proud of him," Kevin answers and bursts into tears. A few pages later, Perrotta elaborates: "It was the phrase little boy that had done it, the sudden memory of an easy weight on his shoulders, Tom perched up there like a king on a throne, gazing down upon the world, one delicate hand resting on top of his father's head, the heels of his Velcro-fastened sneakers knocking softly against Kevin's chest as they walked."

In the second, Kevin's companion, "a pretty but fragile-looking woman named Nora Durst," writes a letter detailing how her family (husband Doug, 6-year-old son Jeremy, 4-year-old daughter Erin) disappeared.

What makes these moments resonate is the role of disappearance in "The Leftovers," which unfolds in the wake of an event very much like the Christian belief in the Rapture and revolves around those left behind. That this Rapture — the simultaneous evaporation of millions of people — appears to have nothing to do with faith or goodness only adds another layer of uncertainty to the world Perrotta describes. "As far as anyone could tell," he writes, "it was a random harvest, and the one thing the Rapture couldn't be was random. … An indiscriminate Rapture was no Rapture at all."

The idea of a Rapture that may not be the Rapture is vintage Perrotta; he's a satirist who likes to poke fun at the vagaries of contemporary life. His best-known efforts, "Election" and "Little Children," take a jaundiced look at high school hierarchies and the quiet desperation of suburban parenthood, respectively, but if "The Leftovers" has an antecedent, it may be his 2007 novel "The Abstinence Teacher," in which a high school sex-ed instructor comes up against evangelicals.

Certainly, it's hard not to find an echo of that book in characters such as Matt Jamison, the former pastor of the Zion Bible Church, who can't accept that he was not among the disappeared. His newsletter — which bears the hysterical (in both senses of the word) title "OCTOBER 14TH WAS NOT THE RAPTURE!!!" — specializes in outing the indiscretions of the chosen, from the bisexual experimentation of a local pediatrician to the infidelity of a businessman. "These people weren't heroes," he tells Kevin at the Departed Heroes' Day of Remembrance and Reflection. "We have to stop treating them like they were." For all his histrionics, Matt is framing a key question in the novel: How do those who did not make the cut come to terms with that and move on?

Such an issue, Perrotta understands, is more complex than it might appear, and it works on several levels at once. At the heart of the novel is a sense not just of loss but also of futility, as if God had asserted himself or herself only to leave everyone more confused. What does it mean that the Rapture has no meaning, that there is no logic as to who was chosen and who was not?

Wisely, Perrotta leaves this open, focusing more on the human story than the metaphysical, which is essentially beside the point. Kevin is a perfect vehicle for that investigation, with his daughter adrift, his son in one cult and his wife, Laurie, in another — a group called the Guilty Remnant, whose members dress in white and silently stalk people to keep them from forgetting the events of the Rapture. For all of them, the normality of the aftermath is its most chilling aspect: the way everything remains as it was. "That was what she'd needed to escape now," Laurie thinks, "the unreality of pretending things were more or less okay, that they'd hit a bump on the road and should just keep on going, attending to their duties, uttering their empty phrases, enjoying the simple pleasures that the world still insisted on offering."

It's worse for those who have lost people: Since no one knows whether they are dead or ascended to heaven, no one knows whether, or how, they should be mourned. Then, there's the world itself, which keeps devolving. "[B]ack then," a soldier named Henning reflects of the period immediately after the Rapture, "just about everyone he knew believed that the End Times were upon them. … [B]ut in the past three years [no one] had emerged as a plausible Antichrist."

The point is that we can't rely on outside structures for meaning, religious or otherwise. This is why Perrotta invokes not just the Rapture but also its date — Oct. 14, with its echo of Sept. 11 — as a metaphor.